Promote OTP-scan-unsupported message to a StringKey (i18n)

[ahmetabdullahgultekin]

Why: The authenticator OTP QR-scan-unsupported message is a hardcoded literal pending promotion to StringKey.OTP_SCAN_UNSUPPORTED, so it is English-only and bypasses the EN/TR string table.

Done when: StringKey.OTP_SCAN_UNSUPPORTED is added with EN + TR values and AuthenticatorScreen consumes it via the resource lookup.

source: androidApp/src/main/kotlin/com/fivucsas/authenticator/ui/AuthenticatorScreen.kt:111

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Migrated from androidApp/src/main/kotlin/com/fivucsas/authenticator/ui/AuthenticatorScreen.kt:111.